Organic Light Emitting Devices (OLEDs) have been fabricated for a long time by vacuum deposition processes. Other techniques such as inkjet printing have been recently thoroughly investigated because of their advantages such as cost savings and scale-up possibilities. One of the main challenges in multi-layer printing is to identify the relevant parameters to obtain a homogeneous deposition of inks on the substrate. To trigger these parameters, such as surface tension, viscosity or boiling point, some additives can be added to the formulation. As an example, (cyclic)siloxanes added in very small quantities (ratio additive to solvent: 0.0001 to 0.5% m/v, WO 03/019693) are remarkably efficient in promoting the wetting and the leveling of various surfaces. They can also be used as a solvent for inorganic semiconductors for inkjet printing (WO 200946148).